Almost all current portable electronic devices rely on rechargeable lithium ion secondary batteries for power. A variety of continuous development efforts of the lithium ion secondary battery have therefore emerged, such as increasing the capacitance capability, power capacity, service life, safety features, and reducing the cost.
The safety concerns of the lithium ion secondary battery mainly result from an increase in the internal temperature of the battery, including improper heating of the battery, overcharging, and short circuit due to contact of the positive and negative electrode materials. When the internal temperature of the battery continuously rises and can not be suppressed, the separator film used to separate the positive and negative electrode materials melts and becomes punctured, leading to excessive short-circuit current, and therefore accelerating the heat build-up of the battery. When the battery temperature reaches 180° C., decomposition reactions of the electrolyte solution and the positive electrode material occur, thereby generating intense heat and releasing large amounts of gas and causing dangers such as fire and explosion.
It is therefore known that, the safety of the lithium ion secondary battery is related to the decomposition voltage of the electrolyte solution and the temperature at which the electrolyte solution experiences thermal fluctuations and damages the dynamic buffer system. The higher the temperature at which the electrolyte solution experiences thermal fluctuations and damages the dynamic buffer system (indicating better high-temperature tolerance), the greater the decomposition voltage of the electrolyte solution (indicating better overcharge tolerance), and consequently the better the safety of the lithium ion secondary battery. Therefore, an electrolyte additive for enhancing the safety of the lithium ion secondary battery is desired to ensure the safety of use for the consumer.